Field of the Invention
The present invention generally relates a spray nozzle assembly for steam-desuperheating, a steam-desuperheating device using the nozzle assembly, and a method of steam-desuperheating using the device.
Description of the Related Art
Many industrial facilities operate with superheated steam that has a higher temperature than its saturation temperature at a given pressure. However, a high amount of heat (superheat) in the steam can damage turbines or other downstream components, and thus, it is necessary to control the temperature of the steam. Desuperheating refers to the process of reducing the temperature of the superheated steam to a lower temperature, permitting operation of the system as intended, ensuring system protection, and correcting for unintentional deviations from the setpoint.
A steam desuperheater can lower the temperature of superheated steam by spraying cooling water into a flow of superheated steam that is passing through a steam pipe. Once the cooling water is sprayed into the flow of superheated steam, the cooling water mixes with the superheated steam and evaporates, drawing thermal energy from the steam and lowering its temperature. If the cooling water is sprayed into the superheated steam pipe as very fine water droplets or mist, then the evaporation of the cooling water in the superheated steam is fast, which is desirable. Conventionally, therefore, much effort has been made to ensure that water droplets have sufficiently small sizes.
Another critical requirement for efficient evaporation is good mixing of injected cooling water in the steam flow. In conventional methods wherein cooling water is sprayed into the steam pipe in a uniform conical pattern, mixing occurs primarily because of turbulence in the steam flow. In search of ways to improve the desuperheating process, the present inventor has conceived segmenting the spray pattern, and means to achieve such effect, to increase the mixing of the steam flow and the injected cooling water, and completed the invention.
Any discussion of problems and solutions in relation to the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.